test changes and additions

Hello,

expr-builtin/q-iri-1.rq and expr-builtin/q-uri-1.rq are both identical: 
both use isUri. I've changed q-iri-1.rq to use isIri instead. I'll 
propose re-approving this test with the 1-byte change next Tuesday.

basic/manifest#prefix-name-1 tests proper handling of prefixes without a 
local name. Glitter passes it.

expr-ops/manifest.ttl is a new manifest containing 7 tests of simple 
numeric ops (<=, >=, +, -, *) that didn't seem to be covered elsewhere. 
Glitter passes all 7.

I also fixed some facet XPath.

I regenerated facets-coverage (though not completely up-to-date) which 
now shows[1] 10 facets uncovered. It should actually be 8.

Summarizing what remains:

isLiteral - needs a test
functions invoked by IRIRef (rather than prefixed name) - needs a test
cast functions - soliciting tests for these from anyone who has them
three ORDER BY variants (ordering with expressions, builtins, and 
functions (e.g. casts)) - needs tests
reversed order of limit+offset - needs test

I'll work on these the rest of the week, though happy to take donations 
of tests from anyone else :-)

Lee

[1] http://www.w3.org/2001/sw/DataAccess/tests/facets-coverage#coverage